Lighting unit



R. F. LESTER LIGHTING UNIT Jan. 15, 1957 Filed Dec. 3, 1953 States LIGHTING UNIT Ray F. Lester, Syracuse, N. Y., assignor to Crouse-Hintls Company, Syracuse, N. Y., a corporation of New York This invention relates to lighting units, and more particularly to a pilot light construction of the explosion proof type for use in hazardous locations.

The invention has as an object 'an explosion proof lighting unit embodying a structural arrangement for mounting the lens of the unit in flame tight relation.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

In the drawings Figure 1 is a vertical sectional view of a lighting unit embodying my invention.

Figure 2 is a transverse sectional view taken on line 22, Figure 1.

The unit consists of a tubular body internally threaded at one end portion. The lighting unit is intended particularly as a pilot light and preferably, the body 10 is threaded externally throughout its entire length to receive jam nuts 11 for mounting the unit in a panel board. A lamp receptacle 12 is mounted in the body 10 intermediate the ends thereof. The lower end portion of the receptacle is recessed at opposite sides to receive terminals 13 for the attachment of lead wires 14. The recesses are filled with cementitious material 16 and the receptacle is enclosed in a sleeve of insulating material. The receptacle is sealed within the body in flame tight relation thereto by a sealing compound 17 positioned in the internally threaded end portion of the body 10.

The lens 20 is fixedly mounted in a sleeve 21 provided at one end portion with internal threads to permit the sleeve to be threaded on the end of the body 10. At the opposite end, the sleeve is formed with an internal bead 22. The outer end portion of the lens 20 is substantially dome shaped, and the inner portion of the lens is formed with a cylindrical surface of substantial axial length. The lens is mounted upon an annular member 23 threaded into the sleeve and positioned to provide a space between the marginal portion of the outer end of the lens and the bead 22. The cylindrical surface of the lens extends concentrically in spaced relation to the inner wall of the sleeve, and the spacing between the ends and the sleeve is filled with a cementitious material 25.

In assembling the lens mount, the annular member 23 is threaded into the sleeve 21 so as to position the marginal portion of the top surface of the lens downwardly, or inwardly, from the bead 22. This spacing provides for 2,777,942 Patented Jan. 15, 1957 a uniform space between the lens and the sleeve for the reception of cementitious material which serves not only to seal the lens in the sleeve, but to also seal the annular member 23 against subsequent movement.

With this arrangement, the sealed annular member 23 forms a rigid abutment for the end of the body, whereby the lens mount may be assembled tightly on the body without exerting any pressure against the glass lens.

What I claim is:

1. A lighting unit comprising a tubular body threaded externally throughout its entire length, a sleeve threaded on one end of the body and being formed with an internal bead spaced outwardly from the end of the body, an annular member threaded in the sleeve and abutting against the end of the body, a lens mounted in the sleeve and being positioned upon said annular member, said lens being formed with a cylindrical portion extending in concentrically spaced relation from the outer end portion of the sleeve, the marginal surface of the outer end portion of said lens being spaced inwardly from said head, the annular space between said lens and sleeve being filled with a cementi-tious material sealing the lens in the sleeve in flame tight relation thereto, the opposite end of said body being threaded internally, a lamp receptacle mounted in the body intermediate the ends thereof and being sealed thereto in flame tight relation, with sealing compound fill= ing the internally threaded portion of said body between said receptacle and the extremity of the body.

2. An explosion proof pilot lighting unit comprising a tubular body threaded externally throughout its entire length, a sleeve threaded on one end of the body and being formed with an internal bead spaced outwardly from the end of the body, an annular member threaded in the sleeve and abutting again the end of the body, a lens mounted in the sleeve and being positioned uponsaid annular member, said lens being formed with a cylindrical portion extending in concentrically spaced relation from the outer end portion of the sleeve, the marginal surface of the outer end portion of said lens being spaced inwardly from said head, the annular space between said lens and sleeve being filled with a cementitious material sealing the lens in the sleeve in flame tight relation thereto, the end of said body opposite said sleeve and lens having an internally threaded portion therein, a lamp receptacle mounted in said body with one end thereof positioned adjacent said internally threaded portion, lead wires connected to said receptacle and extending outwardly through the internally threaded end of said body, and sealing compound surrounding said lead wires and filling the internally threaded portion of said body between said receptacle and the extremity of the body.

References Cited in the file of this patent UNITED STATES PATENTS 1,607,512 Churcher et al Nov. 16, 1926 1,858,994 Kirkland May 17, 1932 1,882,745 Beltz Oct. 18, 1932 2,070,195 Bissell et a1 Feb. 9, 1937 2,316,835 Blood Apr. 20, 1943 2,334,579 Powell Nov. 16, 1943 FOREIGN PATENTS 332,040 Great Britain July 17, 1930 

